This invention relates generally to fluid injection apparatus and methods used at a well site and more particularly, but not by way of limitation, to portable fluid injection apparatus and methods used between a blowout preventer and a choke manifold.
A blowout preventer and a choke manifold are coupled at a flanged connection as known to the art for uses as also known to the art to control the flow of fluid from a well during drilling, completion and production of the well. To insure that this equipment is in proper working condition, pressure tests need to be performed to determine if the equipment has any leaks. Additionally, anti-freeze fluids, such as methanol, sometimes need to be injected into the equipment to prevent freezing.
To perform such pressure testing and fluid injecting operations, it is known that a pump of any suitable type commonly found at a well site can be connected to the top of the blowout preventer or wellhead or to the manifold riser of the choke manifold for injecting fluid used either to perform pressure tests or to provide anti-freeze protection. In performing these operations, the pump equipment is connected during the fluid injection periods and then disconnected thereafter so that the blowout preventer and choke manifold can be properly operated during the drilling, completion or production of the well. Therefore, any time additional fluid needs to be injected, such as to recharge a choke manifold with anti-freeze fluid, the drilling, completion or production operation must be terminated and the injection pumping equipment must be reconnected.
It is also known that when production fluid is flowing from the well and through the blowout preventer, build-ups of a solid residue, known as "bar plugs," occur in the choke line of the blowout preventer. Bar plugs are formed from cuttings, shale, mud and the like found in the fluid which flows from the well and out of the blowout preventer during drilling. Bar plugs present a problem in the operation of the blowout preventer and connected choke manifold because they can move through the outlet of the choke line of the blowout preventer into the connected choke manifold, thereby clogging the choke manifold and preventing proper operation thereof. Because I am not aware of any present apparatus or method which is used to prevent bar plugs from flowing into choke manifolds, there is the need for some type of apparatus and method which can be used with a blowout preventer and connected choke manifold for preventing bar plugs from passing into the choke manifold.
To enhance the utility of such an apparatus and method, it is also desirable for such an apparatus and method to be capable of flowing fluid into the connected blowout preventer and choke manifold to perform pressure tests and to introduce anti-freeze fluid into this equipment. This flow of fluid should be readily repeatable without requiring reconnection and without requiring termination of the normal operation of the blowout preventer and choke manifold. This is desirable because, for example, during certain times continual or repeated flows of anti-freeze fluid are needed to prevent or reduce the formation of hydrates within the equipment, which hydrates freeze and clog the equipment. For example, when a gas zone is encountered and gas is vented or flows from the zone and into the blowout preventor and choke manifold, the flow of the gas "bubble" may continue for a long time, such as for more than an hour. During this time the aforementioned undesirable hydrates can condense from the "bubble" and clog the equipment. This hydrate formation can be prevented or reduced by continually or repeatedly introducing an anti-freeze fluid, such as methanol, into the blowout preventer and choke manifold; a single injection of the anti-freeze fluid prior to the flow of the gas will not suffice because it will flow out of the equipment along with the flow of gas.